This invention relates generally to laser scanners and more particularly to hand-held laser scanners.
Various hand-held laser scanners have been disclosed in the following patent literature: U.S. Pat. Nos. 4,387,297 (Swartz et al.), 4,460,120 (Shepherd et al.), 4,496,831 (Swartz et al.), 4,575,625 (Knowles), 4,593,186 (Swartz et al.), and 4,607,156 (Koppenaal et al.); and European Patent Application No. 86.301458.5 (Barkan et al.). In addition, various hand-held laser scanners are available commercially. For example, Metrologic Instruments, Inc., the assignee of the subject invention, has produced and sold an integral, hand-held laser scanner or terminal constructed in accordance with the teachings of my aforementioned U.S. Pat. No. 4,575,625. That device has been sold under the model designation MS 190 and is a very compact erogonomically designed unit.
As described in my aforementioned U.S. Pat. No. 4,575,625, the MS190 hand-held scanner is a completely self-contained unit including means for scanning a bar code, power supplies, a decoding computer to provide a signal indicative of the information contained in the bar code and communication capabilities to enable the uploading/downloading of data to and from the unit. In particular, the unit basically comprises a laser tube, an optic bench assembly, a rotating reflective polygon and associated motor assembly, a photodetector and associated amplifier and signal processing circuitry, a low voltage power supply, a microprocessor and associated circuitry, a high voltage power supply, a releasable input/output cable connector or plug, an associated input/output cable, and an on/off trigger assembly. All of the foregoing components are mounted within a compact, ergonomically designed housing. The housing itself basically comprises a molded plastic body including a cylindrical handgrip portion and a finger opening located therebelow. The activating trigger is mounted within the finger opening. Various details of the MS 190 scanner housing can be seen in U.S. Pat. No. Des. D281,977, also assigned to the same assignee as this invention.
Operation of the MS190 device is as follows. Upon the actuation of the trigger by the user, and under the control of the microprocessor and associated circuitry in the device, the laser assembly produces a laser beam whose path is directed by the optic assembly and rotating reflective polygon out through an outlet (window) in the housing to impinge upon a bar code disposed opposite the outlet. The rotating reflective polygon sweeps the beam across the bar code. The light reflected off the bar code is of generally uniform spectral distribution so that a portion of it re-enters the housing through the window. From there the reflected light passes through the optic assembly where it is reflected off the rotating polygon and directed to the photodetector. The photodetector and associated amplifier and signal processor forms a part of the signal processing circuitry of the unit which produces digital signals indicative of the make-up of the bar code symbol. The microprocessor and its associated signal processing circuitry decode those signals to provide conventional RS232C signals, e.g., ASCII characters or other conventional serial digital communication signals, via the output connector and cable to any desired peripheral equipment, such as a host computer, an electronic cash register, etc.
The optic bench assembly basically comprises a plurality of mirrors which are oriented to deflect the light in a compact folded path through the unit. In the interest of maintaining critical optical alignment, the mirrors and associated components of the optic bench assembly are rigidly mounted on a support bracket affixed to the front end of the laser tube. The rotating polygon is also mounted on the support bracket. The bracket itself is secured to a printed circuit board or card holding the photodetector, its associated amplifier, and the signal processing circuitry. That circuit board is itself held in place within the housing by a pair of mounting slots forming the inner surface of portions of the walls of the housing. Thus, once the optic assembly is aligned and mounted, it does not utilize the device's housing itself for its support, but only as a nest therefor.
The high voltage supply for the laser is of a conventional, switch mode design, and is in the form of a potted circuit board enclosed in a metal housing or shield located in the rear portion of the plastic housing of the unit.
The laser tube disclosed in my U.S. Pat. No. 4,575,625 is a steel-surround laser tube having a ceramic rear, and an anode portion located within a protective steel encased insulative shield, with a ballast resistor assembly also located within the shield. In early commercial versions of the MS190 device, the steel-surround laser tube was held in place within the handle portion of the housing by plural projections molded into the housing's plastic. This simple mounting arrangement was sufficient from a shock absorbency standpoint, since a steel laser tube exhibits great ruggedness. In the more recent commercial versions of the MS190 device, a glass laser tube has been utilized in lieu of the steel-surround tube. The glass laser tube is, however, located within a protective metal tube and the tube resiliently mounted within the handle portion of the housing by the use of patches of RTV (room temperature vulcanized) rubber material in the interest of shock absorbency.
While the MS190 device has proved very effective for its intended purposes, it still leaves something to be desired from the standpoint of performance (e.g., scanning at a distance), ergonomics (e.g., weight, compactness, balance, ease of manipulation and use, etc.), simplicity and cost of production (e.g., manufacturing, assembling and testing, etc.), and serviceability.